Changes in physical properties of measurement samples, such as liquid crystal, have been measured in the process in which the samples are relaxing from an applied perturbation, such as light and voltage.
Changes in physical properties accompanying a reaction in the measurement samples need to be measured quickly. When reproducible reversible reactions are measured, the step-scan method with a Fourier-transform spectrophotometer is generally used. Fast reversible reactions can also be measured as well by using the step-scan method with the Fourier-transform spectrophotometer (refer to Unexamined Japanese Patent Application Publication No. Sho-61-176824, for instance).
When irreversible reactions, which are isolated phenomena without reproducibility, are measured, the continuous-scan method is generally used. The continuous-scan method, however, cannot be used to measure reactions occurring faster than about 10 milliseconds due to the apparatus mechanism, and it has thus been difficult to measure fast irreversible reactions.
A faster apparatus could possibly be used, but such an apparatus has not yet been developed. Even if such an apparatus were available, it probably would not be adopted as a means for solving the problem because it would be very expensive.
The present inventors have found that the step-scan method is very effective in measuring irreversible reactions as well.
Use of the general step-scan method is limited theoretically to the measurement of reversible reactions. It has been difficult to apply the step-scan method to the measurement of irreversible reactions.
In the physical-property measurement field, there has been a demand for measuring faster irreversible reactions. However, because there has not been an appropriate technique for satisfying this demand and because the continuous-scan method has been used generally to measure irreversible reactions, measurable irreversible reactions have been limited to relatively slow ones.